At least since WWII, light aircraft (General Aviation and, more recently, drones) have been powered by an air cooled, gasoline fueled engine that was typically an opposed six cylinder arrangement. This engine was fueled by very high octane AvGas. The non availability of AvGas in the remote portions of the world has meant that general aviation was unavailable in such area, the very areas of the world that need general aviation services the most. More recently it has been seen that refineries have been reluctant to produce AvGas, thereby stretching the world's supply. While all fuels are not cheap, AvGas has been especially costly.
In contrast to the relative scarcity and costliness of AvGas, relatively inexpensive diesel fuel and/or jet fuel (JP) is much more generally available throughout the world. While the quality of such fuel can vary greatly, a compression combustion engine can burn either diesel fuel or jet fuel (JP) about equally as well. The variances can be recognized as variance in the cetane number of the fuel.
Such a compression combustion engine presents a number of challenges to its designer, including:                variances in cetane rating of the fuel being used must be accounted for;        variances in fuel, atmospheric, and injection abnormalities must be accounted for;        all cylinders should be controlled to deliver substantially equal power;        resonances in the entire drivetrain, comprising engine, transmission and propeller, need to be avoided;        indication of degradation in engine components need to be provided to the pilot as a warning or a caution; and        
Indicated Mean Effective Pressure (IMEP) should be calculated as an indication of engine condition during engine run-ups prior to getting airborne.
There is a need worldwide for an aero engine that can operate on such fuel, yet avoids the challenges noted above.